1. Field of the Invention
This invention relates to a single lens reflex camera in which the battery voltage is boosted and this boosted voltage is used in exposure film winding, or the like.
2. Description of the Prior Art
In the past, as the single lens reflex cameras worked with the help of a voltage of at least 3 volts for driving the exposure control IC and the information displays such as the buzzer and LEDs, all that was required for the voltage to be available was to provide a space for a 4G13 type battery or the like in within the camera housing. Motorizing the film winding of the single lens reflex camera, four Penlight (size AA) batteries had to be used as the electrical energy source of the motor.
Recently, however, to provide the single lens reflex camera with a device for electrically finding a distance from the camera to an object to be photographed, it has been necessary to increase the voltage to 6 volts or more. Also, in the camera having incorporated therein the film winding motor; there is a strong demand for reducing the number of Penlight (size AA) batteries required for driving the motor to two to prevent a large increase in the camera bulk and size. However, cameras for meeting these demands require provision of a DC/DC converter for boosting the power source voltage in the camera bodies for the purpose of obtaining a voltage necessary for driving the distance measuring device, the motor, etc. as mentioned above and also for the purpose of stabilizing the voltage to be supplied to the controlling I.C.--the distance measuring I.C.--the indication element, etc. against the variation of the power source voltage due to the driving of the motor, etc.
The DC/DC converter first oscillates the direct current by using transistors or the like and, after increasing the voltage, is converted to a direct current. Therefore, the incorporation of this apparatus in the camera is liable to produce various electrical accidents. For example, the power line connecting the DC/DC converter with the battery and the ground line (hereinafter described as "GND" line) may oscillate, and the DC/DC converter itself produces induction noise, thereby causing faulty operation of an exposure control IC and light metering IC and a large decrease in the exposure control accuracy. Another disadvantage arising from improper arrangement of the DC/DC converter is that as the outer shape of the camera must be increased to awkward, dimensions it is difficult to design a camera with a smart outer appearance.
With the foregoing in mind, it is an object of the present invention to provide a single lens reflex camera having incorporated therein a DC/DC converter while still permitting the compact form to be preserved by effectively utilizing the substantial volume of the camera.
Another object of the present invention is to provide a single lens reflex camera capable of preventing electrical accidents resulting from the incorporation of the DC/DC converter.
These and other objects of the present invention will become apparent from the following description of an embodiment thereof.